Ignition wires commonly used on automotive engines are entirely flexible and non-self-supporting. Customarily, these wires are draped over the engine components and are often secured at spaced locations by spacers or retainers which are brackets that are secured to the engine components. Typically, the ignition wire is a cable of multiple strands of metal wire such as copper and aluminum wire or is a cotton or plastic fiber that is impregnated with carbon for the necessary conductivity. The carbon impregnated conductors are frequently used since these conductors reduce the amount of radio interference otherwise caused by the automotive ignition system. These conductors commonly bear a distributor terminal connector and, at the opposite end, a spark plug connector and these connectors are commonly surrounded by insulator sleeves or "boots".
A frequent problem in source of ignition failures comprises burnt or destroyed insulation which results from direct exposure of the ignition wires to hot engine surfaces, such as exhaust manifolds. Typically, the exhaust manifolds are located in close proximity to the spark plugs and this location requires that the ignition wires pass in near direct contact with the hot exhaust manifold.